This article is more than 5 years old. Information may no longer be current.
DeFACTO: FFR-CT a novel method for determining lesion-specific ischemia
MUNICH — Compared with standard coronary angiography, noninvasive assessment of fractional flow reserve by CT provided a more accurate determination of which lesions require invasive evaluation, according to new data from the DeFACTO study.
James K. Min, MD, and colleagues evaluated the diagnostic performance of fractional flow reserve (FFR) by CT — FFRCT — for the diagnosis of hemodynamically significant coronary stenosis. The study included 252 stable patients with suspected CAD at 17 centers in five countries. All patients underwent CT, invasive coronary angiography (ICA), invasive FFR and subsequent FFRCT analysis from October 2010 to October 2011, according to a press release. More than 54% of patients had an abnormal FFR determined by ICA.
The primary outcome assessed whether FFRCT could improve the per-patient diagnostic accuracy such that the lower boundary of the one-sided 95% CI of this estimate exceeded 70%, according to the study abstract.
“FFRCT demonstrated improved accuracy over CT for diagnosis of patients and vessels with ischemia,” Min, director of cardiac imaging research and co-director of cardiac imaging at Cedars-Sinai Heart Institute, said at a press conference here.
The diagnostic accuracy for FFRCT was 73%, which did not meet the prespecified primary endpoint for accuracy. In comparison, diagnostic accuracy of CT alone for detecting coronary lesions with stenosis of 50% or greater was 64%. Comparing FFRCT and CT alone for detecting these lesions, FFRCT demonstrated superior discrimination.
The per-patient sensitivity and specificity of FFRCT were also higher than CT alone using an area under the curve analysis (AUC 0.81 vs. 0.68; P=.0002).
Improvement in diagnostic performance was greatest in arterial blockages of intermediate severity. In these patients, there was a more than twofold increase in test sensitivity, from 37% to 82%, with no loss of specificity. In these patients, AUC improved from 0.53 for CT alone to 0.8 for FFRCT (P=.0002).
Additionally, FFRCT computed without additional radiation or imaging, Min said at the conference.
“This is the first large-scale demonstration of patient-specific computational models to calculate physiologic pressure and velocity fields from CT images,” Min said.
The HeartFlow technology investigated in the DeFACTO study is a Web-based service that enables the computation of noninvasive FFR and the identification of which lesions are causing ischemia. The technology computes FFRCT from patient-specific 3D computational models of the aorta, heart and coronary artery tree obtained from CT scan data, and results are transmitted via a secure Web interface as an interactive report, according to information from press release.
“Taken together, these study results suggest the potential of FFRCT as a promising noninvasive method for identification of individuals with ischemia,” Min and colleagues wrote in the Journal of the American Medical Association. “Although the study did not achieve its prespecified primary outcome goal … use of noninvasive FFRCT plus CT among stable patients with suspected or known CAD was associated with improved diagnostic accuracy and discrimination vs. CT alone for the diagnosis of hemodynamically significant CAD when FFR determine at the time of ICA was the reference standard.” – by Katie Kalvaitis
For more information:
Min JK. Hot line I: Late breaking trials on prevention to heart failure. Presented at: the European Society for Cardiology Congress; Aug. 25-29, 2012; Munich.
Min JK. JAMA. 2012;doi:10.1001/2012.jama.11274.
Disclosure: The DeFACTO study was funded by HeartFlow Inc. Dr. Min reports research support from GE Healthcare and Philips Medical.
Perspective
Back to Top
The DeFACTO study brings up all kinds of interesting possibilities in terms of earlier and more accurate diagnosis made by a noninvasive means as opposed to having to perform a catheterization and a catheterization-based FFR. If there is a way to obtain an FFR with a less invasive approach then this could lead to a paradigm shift in the way we approach the assessment of the severity and functional significance of a coronary lesion. This is exciting from a patient standpoint. If you can have this information accrued noninvasively that is a big step forward. Obviously, there remains some work to be done in terms of proving the diagnostic accuracy of CT- based FFR, but these preliminary data are certainly intriguing.